This invention relates generally to digital memory systems and more particularly to digital memory systems which are adapted to store radio frequency signals and to enable subsequent retransmission of such signals.
As is known in the art, it is frequently desired to store a received radio frequency signal and later retransmit such signal. In one such system, the received radio frequency signal is periodically sampled at or above the Nyquist frequency, each sample is next converted into a corresponding digital word, and each digital word is then stored in a digital memory. When it is desired to retransmit, the stored digital words are sequentially read from the memory, generally in the sequence in which they were stored, and such digital words are converted into corresponding voltages to produce a radio frequency signal which is amplified and retransmitted.
With such arrangement, the degree to which the retransmitted radio frequency signals resemble the received radio frequency signals is related, inter alia, to the sampling rate and the bandwidth of the signal being sampled. That is, as the bandwidth of the received signal increases the sampling rate of such received signal must correspondingly increase to satisfy the Nyquist frequency criterion. The bandwidth of the received signal, therefore, is limited, inter alia, by the operating rate of the sampling and digital processing components used in the digital memory system.